Yuzhong Sun

Multi-Tiered On-Demand Resource Scheduling for VM-Based Data Center

The trend of using virtualization for server consolidation is more and more popular in enterprise data center. However, on-demand resource allocation among the concurrent hosted services in such a virtualized environment is still a challenge. In order to optimize resource allocation among services in data center, this paper proposes a multi-tiered resource scheduling scheme which automatically provides on-demand capacities to the hosted services via resources flowing among VMs. We model the resource flowing using optimiza-tion theory. Based on this model, we present a global re-source flowing algorithm in the multi-tiered resource scheduling scheme. This algorithm preferentially ensures performance of some critical services by degrading of others to some extent when resource competition arises. Using our RAINBOW prototype, we evaluate the multi-tiered resource scheduling scheme with the performance improvements for the most critical services up to 9%~16%, which are 75% of the maximum improvement margin, while performance degradation of others is up to 2%, and leads to 1%~5% im-provements in resource utilization than RAINBOW without resource flowing. Compared with the existent scheme, our work leads to 9% less improvements for critical services, while introduces 39% less degradation to low priority ser-vices.

A service-oriented priority-based resource scheduling scheme for virtualized utility computing

In order to provide high resource utilization and QoS assurance inutility computing hosting concurrently various services, this paper proposes aservice computing framework-RAINBOW for VM(Virtual Machine)-basedutility computing. In RAINBOW, we present a priority-based resourcescheduling scheme including resource flowing algorithms (RFaVM) to optimizeresource allocations amongst services. The principle of RFaVM is preferentiallyensuring performance of some critical services by degrading of others to someextent when resource competition arises. Based on our prototype, we evaluateRAINBOW and RFaVM. The experimental results show that RAINBOWwithout RFaVM provides 28%-324% improvements in service performance,and 26% higher the average CPU utilization than traditional service computingframework (TSF) in typical enterprise environment. RAINBOW with RFaVMfurther improves performance by 25%-42% for those critical services whileonly introducing up to 7% performance degradation to others, with 2%-8%more improvements in resource utilization than RAINBOW without RFaVM.

A Two-Tiered On-Demand Resource Allocation Mechanism for VM-Based Data Centers

In a shared virtual computing environment, dynamic load changes as well as different quality requirements of applications in their lifetime give rise to dynamic and various capacity demands, which results in lower resource utilization and application quality using the existing static resource allocation. Furthermore, the total required capacities of all the hosted applications in current enterprise data centers, for example, Google, may surpass the capacities of the platform. In this paper, we argue that the existing techniques by turning on or off servers with the help of virtual machine (VM) migration is not enough. Instead, finding an optimized dynamic resource allocation method to solve the problem of on-demand resource provision for VMs is the key to improve the efficiency of data centers. However, the existing dynamic resource allocation methods only focus on either the local optimization within a server or central global optimization, limiting the efficiency of data centers. We propose a two-tiered on-demand resource allocation mechanism consisting of the local and global resource allocation with feedback to provide on-demand capacities to the concurrent applications. We model the on-demand resource allocation using optimization theory. Based on the proposed dynamic resource allocation mechanism and model, we propose a set of on-demand resource allocation algorithms. Our algorithms preferentially ensure performance of critical applications named by the data center manager when resource competition arises according to the time-varying capacity demands and the quality of applications. Using Rainbow, a Xen-based prototype we implemented, we evaluate the VM-based shared platform as well as the two-tiered on-demand resource allocation mechanism and algorithms. The experimental results show that Rainbow without dynamic resource allocation (Rainbow-NDA) provides 26 to 324 percent improvements in the application performance, as well as 26 percent higher average CPU utilization than traditional service computing framework, in which applications use exclusive servers. The two-tiered on-demand resource allocation further improves performance by 9 to 16 percent for those critical applications, 75 percent of the maximum performance improvement, introducing up to 5 percent performance degradations to others, with 1 to 5 percent improvements in the resource utilization in comparison with Rainbow-NDA.

An Adaptive Resource Flowing Scheme amongst VMs in a VM-Based Utility Computing

In order to optimize the using of server resources which host different services such as Web services, this paper describes an adaptive and dynamic resource flowing scheme amongst VMs in a VM-based utility computing environment called ADVM (adaptive and dynamic virtual machine). In our scheme, VMs adjust their resources (CPU and memory) adaptively to share the physical resources efficiently. ADVM provides an on-the-fly, transparent and lazy resource flowing amongst VMs over a single server. By using dynamic priority and the strategy of adjusting resources, no VM interferes with others even via contention for some resources. To demonstrate the elegance of our strategy, we present a prototype implementation of ADVM. The experimental results indicate that ADVM effectively enforce the system performance based on Xen.

Redar: A Remote Desktop Architecture for the Distributed Virtual Personal Computing

Some popular computing technologies, such as ubiquitous computing, grid computing and thin-client computing, bring people to a much more distributed and pervasive computing environment. Based on these innovative technologies, a distributed virtual personal computing (DVPC) paradigm is coming into being. One of the fundamental challenges in the DVPC design is the virtually integrated but physically distributed desktop system. We proposed Redar, a remote desktop architecture for the DVPC. Redar integrates various user interfaces from diverse service nodes into one virtual desktop, and present the virtual desktop to the ultra-thin user client. The user interfaces currently supported by Redar include the application GUIs as well as the mobile storage interfaces. The key components in Redar are the GUI merger, the virtual desktop manager, the ultra-thin-client and the transport protocols. We have implemented Redar in a DVPC prototype system. According to our evaluation, Redar shows perfect display latency, storage I/O, overhead, scalability and robustness

Recursive cube of rings: a new topology for interconnection networks

In this paper, we introduce a family of scalable interconnection network topologies, named Recursive Cube of Rings (RCR), which are recursively constructed by adding ring edges to a cube. RCRs possess many desirable topological properties in building scalable parallel machines, such as fixed degree, small diameter, wide bisection width, symmetry, fault tolerance, etc. We first examine the topological properties of RCRs. We then present and analyze a general deadlock-free routing algorithm for RCRs. Using a complete binary tree embedded into an RCR with expansion-cost approximating to one, an efficient broadcast routing algorithm on RCRs is proposed. The upper bound of the number of message passing steps in one broadcast operation on a general RCR is also derived.

VMGuard: An Integrity Monitoring System for Management Virtual Machines

A cloud computing provider can dynamically allocate virtual machines (VM) based on the needs of the customers, while maintaining the privileged access to the Management Virtual Machine that directly manages the hardware and supports the guest VMs. The customers must trust the cloud providers to protect the confidentiality and integrity of their applications and data. However, as the VMs from different customers are running on the same host, an attack to the management virtual machine will easily lead to the compromise of the guest VMs. Therefore, it is critical for a cloud computing system to ensure the trustworthiness of management VMs. To this end, we propose VMGuard, an integrity monitoring and detecting system for management virtual machines in a distributed environment. VMGuard utilizes a special VM, Guard Domain, which runs on each physical node to monitor the co-resident management VMs. The integrity measurements collected by the Guard Domains are sent to the VMGuard server for safe store and independent analysis. The experimental evaluation of a Xen-based prototype shows that VMGuard can quickly detect the root kit attacks while the performance overhead is low.

Some remarks on universal re-encryption and a novel practical anonymous tunnel

In 2004 Golle, Jakobsson, Juels and Syverson presented a new encryption scheme called the universal re-encryption [GJJS04] for mixnets [Cha81] which was extended by Gomulkiewicz et al. [GKK04]. We discover that this scheme and its extension both are insecure against a chosen ciphertext attack proposed by Pfitzmann in 1994 [Pfi94]. Another drawback of them is low efficiency for anonymous communications due to their long ciphertexts, i.e., four times the size of plaintext. Accordingly, we devise a novel universal and efficient anonymous tunnel, rWonGoo, for circuit-based low-latency communications in large scale peer-to-peer environments to dramatically decrease possibility to suffer from the attack [Pfi94]. The basic idea behind rWonGoo is to provide anonymity with re-encryption and random forwarding, obtaining practicality, correctness and efficiency in encryption in the way differing from the layered encryption systems [Cha81] that can be difficult to achieve correctness of tunnels.

Green challenges to system software in data centers

With the increasing demand and the wide application of high performance commodity multi-core processors, both the quantity and scale of data centers grow dramatically and they bring heavy energy consumption. Researchers and engineers have applied much effort to reducing hardware energy consumption, but software is the true consumer of power and another key in making better use of energy. System software is critical to better energy utilization, because it is not only the manager of hardware but also the bridge and platform between applications and hardware. In this paper, we summarize some trends that can affect the efficiency of data centers. Meanwhile, we investigate the causes of software inefficiency. Based on these studies, major technical challenges and corresponding possible solutions to attain green system software in programmability, scalability, efficiency and software architecture are discussed. Finally, some of our research progress on trusted energy efficient system software is briefly introduced.

Performance analysis of WonGoo system

Privacy and anonymity on the Internet are gaining increasing attention from both the scientific and the large Internet user community. WonGoo is a peer-to-peer scalable anonymous communication system that provides strong anonymity and high efficiency with layered encryption and random forwarding. It reduces the message overhead and lengthens the covert path. In this paper, we firstly describe the system briefly and evaluate its payload. Then we present a detailed security analysis of the system. The results reveal that the degree of anonymity provided by the system increases with the increase of forward probability and the path length, and reduces with the increase of corrupted nodes. In addition, it is hard to increase its anonymity significantly only by increasing the size of the system.